Underreamer bit or cutter



F. SWAN March 15, 1927.

UNDERREAMER BIT OR CUTTER Filed Aug. 5, 1925 A r f Patented Mar. 15, 1927.

intatto FRED SWAN, GF WICHI'IA, KANSAS.

i UNDERREAMER BIT QR. CUTTER.

Application l'ed' August 5, 1925. Serial No. 43,291.

My invention relates to underreame-rs for enlarging a hole drilled below casing in a drilledwell and particularly relates to underreamers ot' the solid wedge typeY such as the Swan u-nderreamer shown in thev patent to John C. Swan, No. 683,352, dated September 2li, 1901 and other patents to John Swan, in which the cutters or reaming bits slide on a wedge at the lower' end of the reamer body being drawn down on the wedge into collapsed position and then held as the underreamer is lowered through the casing, released as the underreamer passes below the lower end of the casing and drawn up in the wedge into expanded position by a spring.

In pulling out the underreamer as the cutters or reaming bits are brought into contact with the lower end of the casing` their upward movement is momentarily stopped while the upward movement of the reamer body continues with the result that the wedge is drawn up from betweenl the cutters permitting the cutters to move inward into approximately their collapsed position so that their outer faces will be within a circle. of the diameter of the interior of the contact of the upper portion ot the outer face oi the cutters with the interior of the casing the cutting edges of the cutters will be held out of contact with the casing.

With casing made up ot sections connected by screw joints the interior of the casing is so uneven that the trictional contact of the outer faces of the cutters is amply suticient to keep the cutters at the lower end of the wedge and prevent the cutting edges from Contact with the casing and ithas been customary to tallow the ways in order that the cutters will move `freely downward and inward if the upward movement of the cutters is checked by unusual roughness ot the interior of the casing.

Seamless casing is now extensively used and the interior of such casing is of such smoothness that the friction between the outer faces of the cutters, as ordinarily constructed is not suiiicient to hold the cutters down on the wedge as the underreamer is drawn upward, to permit the underreamer to pull freely.

The invention of my present application is designed to overcome this diiiiculty and to provide a construction ot' cutters which will have such frictional contact with the smoothV interior of seamless casing( that the cutters will be kept so near the lower end oi the wedge, and consequently so4 near t0- gether, that the u-nderreamer will pullfreely.

1With the object above explained in view.

my invention consists in the construction hereinafter described and claim-ed.v

Referring to the drawings Figure 1 isa vertical central section oli a drilled well showing an underreamer below the casing with its cutters in expanded position.

Figure 2 is a similar view but showing the underreamer drawn up into the casing.

Figure 3 is a. i'ace view of a cut-ter embodying my invention and Figure l is a side view of the same.

In the drawings 1 indicates seamless casing having interior diameter D1 indicated in Figure 2 in a drilled well hole having an interior diameter D?. 2 indicates an underreamer body ot the kSwan type having at its lower end a wedge 3 on which cutters 1 are movable into and out of expanded position. 5 indicates abutments against which the upper ends ot' the cutters are drawn by spring 6 through spring rod 7 and cross bar 8. Trips 9, as shown in the .lohn C. Swan patent above referred to, provided on their inner ends with extensions 16, are movable in slots formed in the ieamer body toward and from the spring rod 7. When the cutters are drawn down vto the lower ends of the ways so as to permit the underreamer to enter the upper' end of the casing the enlargement 10 on the spring rod is brought below the line of the extensions 16. lVhen the trips are pressed inward these extensions 16 engage the upper faces of the enlargement 10 and hold the spring rod down against the torce oli' spring so that the spring cannot act to draw the cutters upward on their ways into expanded position. The outer faces oie the cutters are thus held out of Contact with the casing. The trips adre held during the downward movement of the underreamer through the casing by the contact oi' their outer ends with the casing, in position to hold the extensions in contact with the upper faces oi' the enlargement 10. i

The cutter l is provided with grooves 11 to engage ways 12 on the wedge 3. At its lower end the cutter is provided with a cutting edge 13 formed on the arc of a circle Yot' a diameter corresponding to D2, the diameter to which the hole below casing soY is to be enlarged. Above this cutting edge 137 the outer face 14 of the cutter f1 is inelined inward at an angle to the ways l1 and is formed on the are of a circle having the diameter Dl that is a diameter1 corresponding to the diameter of the interior of the easing and this outer face is roughened or corrugated by horizontal grooves 15.

r)This outer face 14 is at such angle to the grooves 11 that when the underreainer is drawn into the casing its corrugated sur- `face will throughout its extent be in contact with the interior surface of the casing' l that the resistance thus afforded will be as great as possible notwithstanding the smoothness ofthe inner surface or' the pipe and will keep the cutters down on the Wedge and will keep the cutting edge 13 as far inward and away from the casing as possible.

Having thus described my invention what I claim is :h

In an underreanier of the type in which Cutters are movable on tapering ways into and out of expanded position and are moved into expanded position by a spring, a cutter having a cutting edge at its lower end and having its outer face above the cutting edge inclined inward and formed on an are of a circle corresponding in diameter to the interior diameter of the casing and roughened to increase its rictional Contact with the interior of the casing.

In testimony whereof, l hereunto aiiiX lny signature.

FRED SVAN. 

